Another Visualization of the Protoplanetary Disk Around HL Tau

Here we show a test of a simple IDL code to analyze and visualize the dust structure of protoplanetary disks. We used the impressive image of HL Tau (Figure 1) taken by ALMA for this test. This is not a scientifically calibrated image and we will have to wait to early 2015 for a scientific product. The code averages the radial brightness from the center of the star to get an average radial profile of the disk (Figure 2, top). The anomaly of this profile, with respect to an a priori gaussian model, is created to compare the relative density of the dust regions (Figure 2, bottom). How this relative density relates to the actual density of dust in the disk is another problem. This analysis was done as part of project on interpretations and visualizations of protoplanetary disks (Figure 3).

Figure 2. Average radial profiles of the relative brightness of dust around HL Tau. The profile shows at least three distinct gaps (bottom image) were planets might be forming (9.9, 24.3, 47.1, and 67.6 AU), but other smaller gaps are notable (minimas from the curve). Note that this profile is based on a press release image not calibrated for scientific purposes. Therefore, the relative brightness and the location of the gaps might change with the release of the scientific verification data.

Figure 3. Simple brightness model of the protoplanetary disk around HL Tau derived from the average radial profile. It ignores that some of the dust regions from Figure 1 also show interesting gaps within them. The image is similar to a top view of Figure 1.For reference, the orbit of Neptune is at 30 AU.The size scale is approximate.